Many surgical procedures require vessels or other fluid ducts or tissue conduits and structures to be ligated during the surgical process, such as, for example, veins or arteries in the human body. For example, many surgical procedures require cutting blood vessels, and these blood vessels may require ligation to reduce bleeding. In some instances, a surgeon may wish to ligate the vessel temporarily to reduce blood flow to the surgical site during the surgical procedure. In other instances a surgeon may wish to permanently ligate a vessel. Ligation of vessels or other tissues can be performed by closing the vessel with a ligating clip, or by suturing the vessel with surgical thread. The use of surgical thread for ligation requires complex manipulations of the needle and suture material to form the knots required to secure the vessel. Such complex manipulations are time-consuming and difficult to perform, particularly in endoscopic surgical procedures, which are characterized by limited space and visibility. By contrast, ligating clips are relatively easy and quick to apply. Accordingly, the use of ligating clips in endoscopic as well as open surgical procedures has grown dramatically.
Various types of hemostatic and aneurysm clips are used in surgery for ligating blood vessels or other tissues to stop the flow of blood. Such clips have also been used for interrupting or occluding ducts and vessels in particular surgeries such as sterilization procedures. Typically, a clip is applied to the vessel or other tissue by using a dedicated mechanical instrument commonly referred to as a surgical clip applier, ligating clip applier, or hemostatic clip applier. Generally, the clip is left in place after application to the tissue until hemostasis or occlusion occurs.
Ligating clips can be classified according to their geometric configuration (e.g., symmetric clips or asymmetric clips), and according to the material from which they are manufactured (e.g., metal clips or polymeric clips). Symmetric clips are generally “U” or “V” shaped and thus are substantially symmetrical about a central, longitudinal axis extending between the legs of the clip. Symmetric clips are usually constructed from metals such as stainless steel, titanium, tantalum, or alloys thereof. But, with the advent of high technology diagnostic techniques using computer tomography (CATSCAN) and magnetic resonance imaging (MRI), metallic clips have been found to interfere with the imaging techniques. To overcome such interference limitations, biocompatible polymers have been increasingly used for surgical clips.
Some well known polymeric clips are disclosed in U.S. Pat. No. 4,834,096 and U.S. Pat. No. 5,062,846. These plastic clips generally comprise a pair of curved legs joined at their proximal ends with an integral hinge or heel, and a closure or locking mechanism at their distal ends. Another example of a bio-compatible clip is shown in U.S. Pat. No. 4,671,281, which includes a mechanism to be actuated on a proximal end of the clip for causing the distally extending legs of the clip to converge. However this clip is: (i) rudimentary in construction, (ii) does not provide adequate clip closing or clamping strength, (iii) lacks any complex geometry which would adequately retain the clip in a closed position, and further (iv) is too unstable when closed to be safely applied over vessels. Examples of metal hemostatic clips are shown in U.S. Pat. No. 3,326,216 and U.S. Pat. No. 5,908,430.
In all of the known ligating clips however, there remains a need to improve the effectiveness of clamping about a vessel, while minimizing the damage to the vessel and surrounding tissue. For endoscopic surgical procedures, it is important is use tools and instruments that have the smallest, narrowest profile possible, such as the shafts of a tubular endoscope. Prior art polymeric and metal clips do not lend themselves to deployment through small diameter instrumentation, such as, for example, a ˜5 mm endoscope. Known prior art clips can be very wide profile, especially when in the open position prior to closure and ligation, and thus require larger, wider endoscopic instruments and appliers for use in surgery. It is desirable therefore to provide for a surgical ligation clip that has the narrowest profile possible. It may also be desirable to allow for a clip to be opened again after initial closure, which is especially a problem with known surgical clips, such as metal hemostatic clips. Furthermore, prior art polymeric clips involve locking the distal ends of their legs together in order to clamp down on the vessel or structure being ligated. Such closure of a clip having locking parts at its distal end generally causes or requires dissection, removal, or clearance of additional surrounding tissue, in order to allow the clip's locking features to come together, and/or due to actuation of an applier tool surrounding or applied against the distal clip ends, requiring additional time during a surgical procedure and damage to tissue. In other cases, the user may choose not to prepare a path for the locking features and rely on the locking features penetrating through the tissue. In these cases, the locking feature may have difficulty penetrating the tissue or may have difficulty locking after it has penetrated the tissue. This technique may also result in unintended penetration of tissue or vessels.
Therefore it is desirable to provide a clip which minimizes such dissection of tissue during application. It is further desirable to provide a clip which provides a proper, well-calibrated, reliable clamping force, such that the clip when closed is stable around the vessel ligated.
Accordingly, there is a need to provide an improved surgical ligating clip that serves to reliably secure the tissue or vessel engaged by the clip, while robustly remaining attached to the vessel with a minimum level of damage to tissue.